川西前陆盆地须家河期高分辨率层序格架与古地理演化

结合钻井岩心、测井、野外露头等地质资料以及前人的研究成果,对川西前陆盆地须家河期的沉积特征及古地理演化进行详细研究,依据高分辨率层序地层学理论,建立了层序地层格架,将川西前陆盆地须家河期划分为2个超长期(SLSC1—SLSC2)、3个长期(LSC1—LSC3)、5个中期(MSC1—MSC5)和数十个短期旋回层序。它们在高分辨率层序格架中的岩相古地理特征及演化为:LSC1期为川西前陆盆地形成初期,地层以海相—海陆过渡相沉积为主;LSC2期为湖泛期,同时随着龙门山岛链的逐渐闭合,主要发育湖相—三角洲相沉积;LSC3期为湖盆衰退期,此时龙门山岛链已完全闭合,以湖相和三角洲相沉积为主。

THE FRAMEWORK OF THE HIGH-RESOLUTION SEQUENCE AND THE PALEOGEOGRAPHIC EVOLUTION OF THE XUJIAHE FORMATION IN THE WEST SICHUAN FORELAND BASIN

On the basis of comprehensive study of core, log well, outcrop and conclusion of other paper, the authors have explored the lithofacies and paleogeographic features and the evolution of the Xiujiahe Formation in the West Sichuan Foreland Basin. According to the high-resolution sequence stratigraphic theory, the framework of the sequence was set up: two super long-time sequence cycles (SLSC1—SLSC2), three long-time sequence cycles (LSC1—LSC3), five miedium-time sequence cycles (MSC1—MSC5) and tens of short-time sequence cycles. The features and evolution of the lithofacies and paleogeography of the framework of sequenc were discussed in detail. It was a marine sedimentary sequence at the beginning of LSC1, gradually, delta facies was dominant at the most places. Lake and delta were of main facies in LSC2. From LSC2 to LSC3, delta dominated in the facies.